Portable refrigerant recovery units or carts are used in connection with the service and maintenance of refrigeration systems including an automotive vehicle's air conditioning system. The refrigerant recovery unit connects to the air conditioning system of the automotive vehicle to recover refrigerant out of the system, separate out oil and contaminants, and recharge the system with additional refrigerant.
An oil inject portion of the refrigerant recovery unit is used to put the same amount of compressor oil back into the air conditioning system as was taken out during the recovery process. This may be a visual determination by reading a graduation on the oil drain bottle and on the oil inject bottle, or it may be an automated process.
The oil required in the air conditioning system of a conventional automotive vehicle typically differs from the oil required in a hybrid vehicle. Conventional automotive air conditioning systems typically use polyalkylene glycol lubricant (“PAG”) oil as the refrigerant lubricant or compressor oil, whereas many hybrid vehicle systems use polyolester (“POE”) oil. These oils are generally not compatible with each other. Thus, there is a need to ensure that these various types of oil do not mix with each other between recovery processes.